Water injection system



Dec. 20, 1949 J. DOLZA ET Ax.

WATER INJECTION SYSTEM 6 Sheets-Sheet l Filed Aug. 19, 1944 INVENTOR5 ATTORNEY Dec. 20, 1949 J. DoLzA ET A1.

WATER INJECTION SYSTEM 6 Sheets-Sheet 2 Filed Aug. 19, 1944 Dec. 20, 1949 J. DOLZA ET AL .2,491,484

WATER INJECTION. SYSTEM Filed Aug. 19, 1944 6 Sheets-Sheet 3 Carbure Z'ar Z/,

, im?? iv dariary if fwperc/aryer ATTORNEY@ Dec. 20, 1949 Filed Aug. 19, 1944 J. DOLZA ET AL WATER INJECTION SYSTEM 6 Sheets-Sheet 4 Dec. 20, 1949 J. Dom/x ET AL 21.491484 WATER INJECTION SYSTEM y Filed Aug. 19, 1944 6 Sheets-Sheet 5 ww myZ Dec. zo, 1949 DOLZA ETAL 2,491,484

WATER INJECTION SYSTEM 9 ATTORNEY@ Patented Dec. 20, 1949 WATER INJECTION SYSTEM John Dolza and Milton A. Trisler, Indianapolis, Ind., and Clyde R. Paton, Birmingham, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application August 19, 1944, Serial No. 550,232

l Claims. (Cl. 12S-25) This invention relates to a system of control of water injection in the fuel mixture of a supercharged aircraft engine and to the control of intake manifold pressure incident to water inlection.

An object of the invention is to cause water injection to take place automatically when the difference between intake manifold pressure and altitude pressure or carburetor impact pressure attains a certain value. and to make it possible to obtain certain high manifold pressures only so long as the water injection is operating, and automatically to limit manifold pressure to a lower value safe for engine operation without detonation when water injection ceases.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 shows diagrammatically a carbureting and supercharging system with which the present invention may be used.

Fig. 2 is an enlarged sectional view of a fuel nozzle shown in Fig. 1.

Figs. 3, 4 and 5 show a system of control of water injection and a coordinated control of intake manifold pressure provided by a throttle controller TC and a fluid coupling controller FC.

Fig. 6 is a longitudinal sectional view of the 'throttle controller TC of Fig. 4.

Fig. 7 is a sectional view on lines I-l of Figs.

f 8 and 9.

Fig. 8 is a sectional view on line 8-3 of Fig. 6. Fig. Slis a sectional view on line 9-9 of Fig. 6. Fig. 10 is a fragmentary sectional view of the fluid coupling controller FC of Fig. 4.

Fig". ll is an enlarged sectional view of the water metering device shown in Fig. 5.

Fig. 12 is a diagrammatic view of a hydraulic coupling.

In Fig. l, the reference character III indicates an internal combustion engine with a main centrifugal supercharger which includes an impeller II and an auxiliary centrifugal supercharger which includes an impeller i2. The impeller II of the main supercharger is driven from the crankshaft of the engine at a speed proportionate to the speed of the engine through gearing which is indicated generally by the reference character I3. The impeller I2 of the auxiliary supercharger is driven from the crankshaft of the engine at a speed which varies with respect to the speed of the engine through elements of the gearing 2 I3, a gear I4, gearing I5, a universal joint I8, a fluid coupling |'I and gearing I8.

From a point at which air is forced into it by movement of the airplane to the intake side of the auxiliary supercharger there extends a duct I9 to whose outer end there is connected a scoop 20 which faces in the direction of movement of the airplane.4 In the duct I3 between the scoop 20 and the auxiliary supercharger there is interposed a fuel metering device 2|, such as used in the Stromberg injection carburetor, which meters fuel at a rate which bears the desired relation to the rate of flow of air through the duct. To regulate the rate of flow of air through the duct, there is incorporated in the fuel metering device a butterfly type throttle valve 49. From the discharge side of the auxiliary supercharger to the intake side of the main supercharger extends a duct 22 into which projects immediately in advance of the impeller I I of the main supercharger a fuel nozzle 23 which is connected to 'the fuel metering device 2I by a tube 24.

To advance fuel to the metering device 2| and, thence, to the fuel nozzle 23 through the tube 24 there is provided a fuel pump 25. The fuel pump 25 includes a body 26 with a fuel intake opening connected to the fuel tank of the airplane by a pipe 21 and a fuel discharge opening connected to the metering device 2| by a pipe 23 and an impeller 29 driven by the engine at a speed proportionate to the speed of the engine I0 to draw fuel into the intake opening and discharge it from the discharge opening. In the body 26 of the fuel pump there is yprovided a by-pass 30 through which fuel may return from the discharge opening to the intake opening and in this by-pass a valve 3|. The valve 3| is urged to position to close the by-pass by a spring 32 and connected to a flexible diaphragm 33 Whose inner side is exposed to the pressure of 'the fuel in the by-pass so that the valve will open when and remain open as long as the pressure of the fuel at the discharge opening of the pump exceeds the pressure to which the-outer side of the diaphragm is exposed by a selected amount to the end of maintaining constant the pressure `at which fuel is discharged from the pump.

To regulate the discharge of fuel from the nozzle 23 there is provided within the nozzle a conical valve 34 with a stem 35 which is urged by a spring 36 to the position in which it closes the discharge orifice 31 in the nozzle and connected to a flexible diaphragm 3B whose inner side is exposed to the pressure of the fuel in the nozzle SQ that the valve will open and fuel will be iniected into the duct 22 when the pressure of the fuel in the nozzle exceeds the pressure to which the outer side of the diaphragm is exposed by a certain amount and the valve will remain open and fuel will continue to'be injected into the duct 22 as long as the difference in pressure exceeds this amount.

When the engine I is operating. air enters the scoop and passes therefrom through the duct I3, the metering device 2| and the auxiliary supercharger into the duct 22. Fuel is injected through the nozzle 23 into the air in the duct 22 and with it passes through the main supercharger into the cylinders of the engine.

To insure injection of fuel into the duct 22 in the form of a spray which will readily be entrained by the air in the duct. it is, of course, necessary to maintain the pressure of the fuel within the fuel nozzle 23 at a value well above that of the air in the duct 22 and the effective area of the orifice 31 in the fuel nozzle below a value which varies with the rate at which fuel is delivered to the fuel nozzle. To insure these things. it is necessary that the pressure at which fuel is discharged from the fuel pump be maintained above a certain value and the valve 34 in the fuel nozzle be prevented from opening too far. To do these things it is necessary to prevent the pressure on the outer sides of the diaphragms 33 and 38 of the fuel pump and the fuel nozzle falling below a selected value and to insure iniection of fuel into the duct 22 at a rate which bears the desired relation to the rate of flow of air to the engine and in the most desirable form it is preferable to maintain the pressure on the outer sides of the diaphragms constant.

Through the fluid coupling I1 the rate at which the impeller l2 of the auxiliary supercharger is driven is so regulated that the pressure in the duct 22 is maintained at about that of the atmosphere at sea level under all conditions of atmospheric pressure which obtain up to a selected altitude except when the engine is operating at low speeds when it is impracticable so to regulate it. At altitudes greater than the selected altitude within the range within which the engine ID is intended to operate the rate at which the impeller of the auxiliary supercharger is driven is, through the fluid coupling, so regulated that the pressure in the duct 22 is, except, of course, when the engine is operating at low speeds, maintained at a value which while lower than that at which it is maintained up to the selected altitude is still higher than that of the surroundingr atmosphere. The pressure in the duct 22 is, consequently, at times higher and at times lower than the pressure of the surrounding atmosphere.

To maintain the pressure on the outer sides of the diaphragms 33 and 38 of the fuel pump and fuel nozzle as nearly constant as possible at all speeds of the engine I0 under all conditions of atmospheric pressure. there is provided on the fuel pump a cover 39 for the diaphragm 33 and on the fuel nozzle a cover 40 for the diaphragm 38. The interiors of these covers are connected to the interiors of the scoop 20 and the duct 22 through a valve so constructed that the higher of the pressures of the air in the scoop and the air in the duct 22 is applied to the outer sides of the diaphragms 33 and 38. The valve referred to is indicated in the drawing by the reference character 4|. It includes a hollow body 42 within which there is a exible diaphragm 43. The connections between the interiors of the covers 33 and 40 and the interiors of the scoop 20 and the duct 22 which were mentioned are afforded by pipes 44, 45, 45, 41 and 43. The pipes 44 and v45 are connected. respectively, to the interior of the cover 38 and the interior of the cover 40. The pipe 45 is connected to the pipes 44 and 45 and to the interior of the body of the valve 4I so that it communicates with it on both sides of the diaphragm 43. The pipe 41 is connected to the interior of the scoop and to the interior of the body of the valve 4I on one side and the pipe 48 is connected to the interior of the duct 22 and to the interior of the body of the valve 4l on the other side of the diaphragm 43.

This arrangement insures that the outer sides of the diaphragms 33 and 33 will always be subjected to the higher of the pressures of the air in the scoop 28 and of the air in the duct 22 and, consequently, that the pressure on the outer sides of the diaphragms will be maintained as nearly constant as possible at all speeds of the engine under all conditions of atmospheric pressure. If the pressure of the air in the scoop becomes higher than the pressure of the air in the duct 22, the diaphragm 43 will op over to a position in which it blocks communication between the duct 22 and the interior of the body of the valve and, consequently, as long as this condition obtains the outer sides of the diaphragms 33 and 38 will be subjected to the pressure of the air in the scoop. If the pressure of the air in the-duct 22 becomes higher than the pressure of the air in the scoop, the diaphragm will flop over to a position in which it blocks communication between the scoop and the interior of the body of the valve and, consequently, as long as this condition obtains the outer sides of the diaphragms 33 and 38 will be subjected to the pressure of the air in the duct 2'2. The condition first mentioned obtains, as previously stated, only when the engine is operating at low speeds.

The arrangement which has been disclosed is not limited to use in conjunction with the particular carbureting apparatus which has been illustrated and described. It can also be used in conjunction with carbureting apparatus which includes one or more superchargers on whose engine side or sides the fuel is injected. It can also be used in conjunction with carbureting apparatus which includes one or more superchargers on whose atmospheric side or sides the fuel is injected but in the case of carbureting apparatus of this type it is not so important to apply the arrangement to the fuel nozzle. In the case of carbureting apparatus which includes a fuel pump of other than the by-pass type the arrangement may be applied to the fuel nozzle only.

l The water injection system comprises a tank 58 (Fig. 5) for containing alcohol-water mixture the highest level of which is indicated by line 5i. A float 52 carried by arm 53 operates a shaft 54 of an electrical quantity transmitting device 55 which controls through the wires a, b, c and d, a quantity meter 55. The tank is filled through an inlet 51 closed by a cover 58 after filling. Inlet 51 is connected with a vent pipe 51a.A Tank outlet 53 connects with a pump 50 similar to fuel pump 25 (Fig. 1) and having a diaphragm chamber connected by pipe 5 I with a pipe 52 connected with pipe 44 (Figs. 1 and 3) connected with vent selector valve 4|. Pipe 52 is connected with the diaphragm chamber of a boost pump not shown. Thus, outlet pressures of all the pumps are controlled by vent selector valve 4 I. s

The pump 60 is driven by an electric motor 18 (Fig. 5) having its negative terminal grounded and its positive terminal connected by wire 1| with contact 12 of a relay 15 having a movable contact 'i3 for bridging contacts 12 and 14. Contact 13 is connected with a solenoid amature 1I which moves upwardly when coil 11. is energized. Contact 14 is connected by wire 18 with a battery I (Fig. 4) whose negative terminal is grounded.

Wire 19 connected to coil 11 and wire 18 connected to contact 14 are connected with a snap action switch 82 located in a housing 83and having a push button 84 engaging a stlrrup 05 located between the adjacent free ends of bellows 86 and 81 which have their respective opposite ends restrained by walls 88 and 89 respectively of a housing 90 attached to a support 9i. Bellows 81 is evacuated to provide an aneroid. Bellows 86 is connected by pipes 92 and 93 (Figs.

3 and 4) with the scroll or outlet of the engine stage supercharger having the impeller I Housing 90 is connected with the carburetor anterior to the value 49 vby pipes 94 and 95. Thus the switch 82 (Fig. 4) is caused to close in response to a certain difference between engine stage scroll pressure (or intake manifold pressure) and impact pressure (or altitude pressure). The impact pressure is the pressure maintained in the intake anterior to the valve 49. This pressure is determined in part by speed of flight because the scoop 20 at the end of the intake pressure faces in the direction of movement of the aircraft. Also this pressure varies with the altitude. For example, switch 82 is set to close at and above a scroll pressure of 58.5" Hg abs., which corre sponds to a. manifold pressure of 57" when the carburetor impact pressure is 29.9" Hg abs. The effect of the difference in area of the bellows 81 and 88 is that, when the carburetor impact pressure becomes 13.6" Hg abs., the switch B2 will be closed at and above a lower scroll pressure, for example, 53" Hg or a manifold pressure of 51.5" Hg.

'I'he outlet of pump 60 (Fig. 5) is connected by a strainer 90 and acheck valve 99 with the water metering unit |00 which controls the flow of alcohol-water mixture through a pipe |0| (Figs. 4 and 3) connected with the nozzle 23. The unit |00 (Fig. 11) comprises a chamber |02 closed by a diaphragm |03 `and connected by pipe |03a (Fig. with thatportion of the carburetor 2| which is under the pressure of unmetered fuel. A rod |04 `connects diaphragm |03I with a dlaphragm |05 covering a chamber |01. The space between the diaphragms is vented at |06. There fore the pressure on diaphragm |05 from rod |04 is transferredto chamber |01 as unmetered fuel pressure unaffected by changes in altitude. A balanced valve |08 is urged upwardly by a spring |09 against seats ||0 and Valve |08, being engaged by pin |04, maintains metered fuel pressure in chamber |01. Metered fuel pressure on the lower side of diaphragm` i2 (transferred by passage H3) and nozzle pressure on the upper side of diaphragm |i2 imposes a metering head on a metering valve I I 4 which is the same metering force imposed on the jets of the carburetor. The contour of the valve ||4 is such and the size of the metering orifice ||5 is so calibrated as to sive a. flow of alcohol-water mixture suicient to suppress detonation as the air flow is increased to maximum powers. The alcohol-water mixture is injected through the spray nozzle 29 along with the gasoline.

We make no claim to the water metering unit thus far described. We do claim, however, the provision of means responsive to the proper flow of water from the pump out through the nozzle 23 for causing water pressure to be transmitted toa diaphragm chamber for the purpose of controlling other instruments such as the throttle controller TC and-the fluid coupling controller FC. Such means will now be described.

Before water discharged from the pump can reach the metering valve |08 it must pass around a valve |20 loaded by a spring |2i or through an orifice |22 in the valve |20. When the water is ilowing properly the pressure in chamber |23 exceeds the pressure in chamber |24 by about 1 1b. per sq. inch. Then a. diaphragm |25 will move left against the action of a spring |26 to move a valve |21 from its seat |28 to permit water 'to flow out passage |29 connected by pipes |30 and |3| with diaphragm chambers |32 (Fig. 4) and |33 (Fig. 3) respectively and by pipe |34 with a pressure operated switch |35 (Fig. 5) which then closes to cause a lamp |36 to burn to indicate the operation of the water injection apparatus. The diaphragm |42 closing chamber |32 (Fig. 4) then operates a valve |40 which causes derichment of the fuel mixture. The diaphragm |43 (Fig. 6) then operates a device (to be described later) for rendering ineffective a device which limits the intake manifold pressure so that higher pressures safe for engine operation with water injection may be obtained. When the water becomes exhausted valve |21 closes and the water pressure in the diaphragm chambers |32 and |33 quickly falls because they are connected with the tank 50 through a passage |31 and a vented :return pipe |38. If the passage between the metering unit |00 and the outlet of nozzle 23 becomes clogged, the pressure differential between chamber |23 and chamber |24 rdecreases and spring |26 closes the valve |21; and the pressure in the diaphragm` chambers |3| and |33 falls, as before. Passage |39 (Fig. 11) provides for return of liquid in chamber |23 to the tank 50.

The throttle controller TC (Figs. 3 and 4) of which the chamber |33 is a part and the uid coupling controller FC coordinated therewith are the subject matter of the copending application of Dolza et a1., Serial No. 498,968 filed August 17, i943. Brieiiy, the controller TC comprises a pilotoperated main control lever |50 which operates a shaft |5|` carrying a lever |52 connected by a link |53 with a cam lever |54 (Fig. 3) ixed to a shaft |55 carrying a pressure selecting cam |56 (Fig. 6) against which a spring |51 urges ay lever |58 pivoted at |59 on a bridge |60 connecting the adjacent free ends of bellows |'6i and |62 having their remote ends iixed to housing members |63 and |64 respectively. Bellows |6i, which is evacuated to provide an aneroid, encloses springs |65 and |66; and bellows |62, which is connected with pipe 93 (Fig. 3) in a manner to be described, encloses a spring |61. These springs are so constructed and calibrated that the pivot |59 moves in a definite relation to changes in engine stage scroll pressure and to intake manifold pressure. The bellows |62 encloses a second spring |68 located within a tube |10 having a flange |1| attached to housing |64. Spring |68 surrounds a rod |12 fixed to the free end of bellows |62 and carrying an adjustable self-locking nut |131 normally spaced from the spring |68. When a certain manifold pressure is attained, the bellows |62 The position of piston |8| is controlled by a valve |88 slidable in a guide 88a which controls the connection between a fluid pressure inlet port |84 and distributing ports |85 and |86. Ports |85 connect with groove |81 in valve guide |88a connected by passages |88 and |88 (Fig. 8) with the left end of the cylinder. Ports |86 connect with groove |80 in valve guide |83a connected by passage |8| with the right end of the cylinder. The discharge of low pressure fluid from the cylinder |80 into the bellows chamber |82 is either from the left end of cylinder |80 through passages |88, |88, groove |81, port |85 and guide |88a or from the right end of cylinder |80 through passage |8|, groove |80, ports |88, guide |83a and passages |88 and |84 (Fig. 8). The hydraulic iluid under pressure is conducted from the engine oil pump (not shown) through pipe 200 (Fig. 3) connected by passages and 202 and valve guide groove 208 (Fig. 6).

The servo-motor control valve |83 is under the joint control by the cam |58 (controlled by the pilot through lever |50) and by the pressure in bellows |82 connected by passages 2|0, 2|| and 2|2 (Fig. 8) and by pipe 88 (Fig. 3) with the scroll or outlet of the engine stage supercharger.

The engine throttle valve 48 (Fig. 4) is under joint control by the pilot (through lever |50) and by the servo-motor through a floating lever 220 pivoted at. 22| on an arm 222 attached to shaft |5I. Lever 220 is connected at 228 with a link 22'4 connected with a ylever 225 which rotates a shaft 228 carrying the valve 48. Lever 220 is connected at 280 with a link 28| connected with the rod 282 which is attached to the piston |8|.

Manual control of the valve 48 is suflicient for safe landing in case of failure of oil pressure in cylinder |80 in which case the spring |82 returns the piston |8| to the right as shown vin Fig. 6. The control of the valve 48 by the servo-motor corrects for any divergencies between en'ngine intake manifold pressure or engine stage scroll pressure and the pressure selected by the cam |58 which is manually controlled.

When water injection is not used, the cam |58 controls the lever for pressure selections up to about 60"l Hg abs., for example, that being the maximum pressure safe for engine operation without water injection. If a high pressure is selected, when there is no water injection, the

lever |58 is stopped by a rod 240 guided by a4 sleeve 24| in housing |88 and urged by a spring 242 against a lever 248 pivoted at 244 and carrying a pin 245 received by a notched lever 248 attached to a shaft 241 carrying a notched lever 248 receiving a pin 248 attached to a rod 250 guided by a sleeve 25| and connected with the diaphragm |48. A spring 252 urges the rod 250 right against an adjustable stop screw 258 so long as the water injection apparatus is not functioning. When water injection is operating. the pressure in chamber |88 overcomes the spring 252 and moves the diaphragm |48 left: and the rod The controller FC (Fig. 3), which controls the status of the fluid coupling |1 (Fig. l) and hence the speed of the auxiliary supercharger impeller I2, is constructed somewhat like the controller TC. It has a servo-motor including a piston rod 280 (Fig. 3) connected with a tube or scoop (not shown) which determines the rotation level of hydraulic fluid in the coupling I1. This construction is fully disclosed in the copending Dolza application referred to. The control valve of this servo-motor is controlled by parts similar in construction and arrangement to certain parts of the controller TC. The similar parts are marked with the same reference numbers with the prime aiiixed.

Bellows |82' (Fig. 10) of controller FC is connected by passages 2|0' and 2|.|' with pipe 85 (Fig. 3) with the carburetor upper deck. Hence bellows |82' responds to variation in impact pressure which varies with altitude and airplane speed. Cam shaft |55' (Fig. 10) is attached to a lever 28| (Fig. 3) connected by link 282 and pin 283 with the piston rod 280. Therefore the coupling scoop of the hydraulic coupler |1 (Fig. l) is controlled by pressure altitude according to a predetermined schedule of changes thereof.

The specic form of iluid coupling by means of which the auxiliary supercharger can be operated at innitely variable speed is not part of f the present invention, nor is the specific construction of the means for eil'ecting operation of such coupling. The last mentioned means which is shown herein and which is described immediately above is of the same commotion as that disclosed in the application of Dolza et al., Serial No. 520,878 and in Fig. 12 there is shown a diagrammatic view of the coupling and means for controlling its action which is disclosed in the said application of Dolza et al.

This coupling which is designated in its entirety by the reference number I1, comprises, as shown, a driven vane member 800 attached to a hollow shaft connected with gear |8. A driving vane member 802 is provided and is attached to an engine driven shaft 808. To the driving vane member there is attached an annular hood 804 -which surrounds both vane members of the coupling. The motion transmitting fluid for the coupling passes through the hollow shaft 80| and then radially between the coupling, or vane, members. From the vane member 802, oil passes out through anumber or holes 805 into the hood 804, so that the rotary level of the motion transmitting nuid in the hood is substantially the same as within the vane members. In order to vary the slip percentage, or coupling ratio, the rotary fluid level within the coupling is varied by changing the position of a hollow coupling scoop tube 808 through which the motion transmitting fluid may flow from the coupling. The further the end of the scoop tube is from the axis of the coupling, the lower the iluid level within the coupling will be and the greater the slippage. As the end of the tube is moved toward the axis, the slippage will be decreased and the coupling ratio increased. The coupling scoop tube is automatically adjusted by movement of the piston rod 28| to which said scoop tube is operatively connected in any suitable manner.

supercharger in relation to a decreasing scale of altitude pressure values. This is accomplished by shifting axis of shaft lil' counterclockwise (Pig. as the pressure selections are increased. To do this. the shaft |85' is mounted eccentrically in a shaft 210 (dot-dash circle in Fig. 10) carrying a lever 21| (Fig. 3) connected by a link 212 with a. lever 213 pivoted at 214 on the controller, '10. Lever 213 has an opening receiving a roller 215 pivotally supported by an arm lila of lever |54 which is engageable with a cam surface 216 provided by lever 213. This cam surface 218 is urged upwardly by a spring 211 attached to lever 21| and to the housing |64' of controller FC. When the pressure selection is high enough to cause the roller 215 to move right past the portion :n of the cam surface 21B. lever 21| will move up under the action of spring 211 to cause lever 28| and shaft |55' to move counterclockwise and the cam |56' to be shifted in such manner as to cause the controller FC to raise the schedule of auxiliary supercharger speeds in relation to the scale of altitude pressures. To prevent the attainment of an auxiliary supercharger speed such as to cause detonation when the altitude pressures fall to certain low values. the shaft |55' is caused to be bodily moved clockwise after a certain movement of the piston rod 260 to the left has taken place. This is effected by a stop screw 280, carried by lever 26|, which engages the lever 21| which begins to rotate the shaft 21|) (eccentrically supporting the shaft |55') after a certain left movement of piston rod 260 has taken place thereby causing the rod 260 to stop, thereby limiting the auxiliary supercharger speed to a value in the schedule of altitude pressure vs. supercharge speed for an intake pressure value lower than that which had been selected. In this way, the auxiliary supercharger operates according to a higher schedule of speed vs. altitude pressure when the altitude pressures are relatively high; and when the altitude pressures are relatively low, the auxiliary supercharger speeds are lowered automatically to prevent detonation.

The extent to which the altitude-pressure vs. speed schedule can be raised depends on whether water injection is used. When it is not used, the extent to which lever 213 can move upwardly lunder the action of spring 211, when high intake pressures are selected. is limited by the engagement of the lever 213 with a stop screw 290 carried by a lever 29| attached to shaft 241. When water injection is used, lever 29| moves up to take screw 290 entirely out of the path of movement of lever 213, so that it can follow the roller 215 into any position thereof in the higher pressure selecting positions of the leverVV |54.

From the foregoing description, it is apparentintake pressure control means as to make it pos. sible to obtain intake manifold pressures safe for engine operation'with water injection.

n The term scroll which is used in this specification is a term commonly used in this art and refers to the supercharger housing.

While the disclosed embodiment of the present invention includes a throttle controller coordinated with a controller of the speed of an auxiliary supercharger driven by the engine, it is to be understoodthat the present invention is applicable to other supercharging systems and controls therefor either with or without the variable speed auxiliary supercharger.

What is claimed is as follows:

1. A system of control for a supercharged internal combustion engine comprising, in combination, a throttle valve controller having datum adjusting means providing for selection of an engine intake pressure to be maintained and means under control by intake pressure and by said datum adjusting means for so positioning the engine throttle valve as to obtain the selected 1 pressure, a control lever for operating the datum adjusting means, a supercharger connected with the engine intake, variable speed means for driving the supercharger and having a speed changing element, a regulator having provisions under control by altitude pressure and by the control lever for so positioning the speed changing element as to give a supercharger speed necessary to obtain the selected pressure at varying altitudes. apparatus for effecting the injection of a liquid into the engine intake, means normally operative to limit the speed obtained by operation of the speed regulator and the pressure obtained by operation of the valve controller to values required for safe operation of the engine without liquid injection, and means responsive to the proper functioning of the injection apparatus for disabling said limiting means.

2. A system of control for a supercharged internal combustion engine, comprising in combination, a throttle valve controller having datum adjusting means providing for selection of an engine intake pressure to be maintained and means under control by intake pressure and by said datum adjusting means for so positioning the engine throttle valve as to obtain the selected pressure, a control lever for operating the datum adjusting means, a supercharger connected with the engine intake, variable speed means for drivlng the supercharger and having a speed changing element, a regulator having provisions under control by altitude pressure and by the control lever for so positioning the speed changing element as Vof the speed regulator and the pressure obtained by operation of the valve controller to values retween engine stage scroll pressure and carburetor impact pressure or altitude pressure, means for controlling engine intake pressure and normally operative to limit the pressure to less than border-line detonation pressure when water iniection is not operating, and means responsive `to the ilow of water-alcohol mixture from the quired for safe operation of the engine without liquid injection, and means responsive to the flow of liquid through the nozzle for disabling said limiting means.

3. A system of control for a supercharged internal combustion engine comprising, in combination, a throttle valve controller having datum adjusting means providing for selection of an engine intake pressure to be maintained and means under control by intake pressure and by pump to theY spray nozzle for so modifying the said datum adjusting means for so positioning amines the engine throttle valve as to obtain the selected pressure, a control lever for operating the datum adjusting means, a supercharger connected with the engine intake, variable speed means for driving the supercharger `and having a speed changing element, a regulator having provisions under control by altitude pressure and by the control lever for so positioning the speed changing element as to give a supercharger speed necessary to obtain the selected pressure at varying altitudes, a liquid supply tank, a liquid spray nozzle in the engine intake, a pump for forcing the liquid from the supply tank through the nozzle, means under control by engine intake pressure and altitude pressure for causing the pump to operate, means normally operative to limit the speed obtained by operation of the speed regulator and the pressure obtained by operation of the valve controller to values required for safe operation of the engine without liquid injection, and means responsive to the flow of liquid through the nozzle for disabling said limiting means.

4. A system of control for a supercharged internal combustion engine comprising, in combination, a throttle valve controller having datum adjusting `means providing for selection of an engine intake pressure to be maintained and means under control by intake pressure and by said datum adjusting means for so positioning the engine throttle valve as to obtain the selected pressure, a control lever for operating the datum adjusting means, a liquid supply tank, a liquid spray nozzle in the engine intake, a pump for forcing the liquid from the supply tank through the nozzle, means normally operative to limit the pressure obtained by operation of the valve controller to avalue required for safe operation of the engine without liquid injection, fluid pressure operated means for disabling said limiting means,

a valve for controlling the fluid pressure operated means, and means responsive to the flow of liquid for actuating said valve.

5. A system of control for a supercharged internal combustion engine comprising, in combination, a throttle valve controller having datum adjusting means providing for selection of an engine intake pressure to be maintained and means under control by intake pressure and by said datum adjusting means for so positioning the engine throttle valve as to obtain the selected pressure, a control lever for operating the datum adjusting means, a liquid supply tank, a liquid spray nozzle in the engine intake, a pump for forcing the liquid from the supply tank through the nozzle, means normally operative to limit the pressure obtained by operation of the valve controller to a value required for safe operation of the engine without liquid injection, means operated by pressure of the liquid discharged from the pump for disabling said limiting means, a normally closed valve for establishing a connection between the pump outlet and the liquid pressure operated means, and means responsive to the flow of liquid through the nozzle for opening said valve.

6. A system of control for a supercharged internal cumbustion engine comprising, in combination, a throttle valve controller having datum adjusting means providing for selection of an engine intake pressure to be maintained and means under control by intake pressure and by said datum adjusting means for so positioning the engine throttle valve as to obtain the selected pressure. a control lever for operating the datum adjusting means, a liquid supply tank, a liquid spray nozzle in the engine intake, a pump for forcing the liquid from the supply tank through the nozzle, means normally operative to limit the pressure obtained by operation of the valve controller to a value required for safe operation of the engine without liquid injection, iiuid pressure operated means for disabling said limiting means, a valve for controlling the fluid pressure operated means, a spring loaded valve interposed in the path of flow of liquid from the pump to the nozzle, and meansresponsive to the differential of pressure of the liquid anterior and posterior of said interposed valve for actuating the valve for controlling the iluid pressure operated means.

7. A system oi control for a supercharged internal combustion engine comprising, in combination, a throttle valve controller having datum adjusting means providing for selection of an engine intake pressure to be maintained and means under control by intake pressure and by said datum adjusting means for so positioning the engine throttle valve as to obtain the selected pressure, a control lever for operating the'datum adjusting means, a liquid supply tank, a liquid spray nozzle in the engine intake, a pump for forcing the liquid from the supply tank through the nozzle, means normally operative to limit the pressure obtained by operation of the valve controller to a value required for safe operation of the engine without liquid injection, means operated by pressure of the liquid discharged from the pump for disabling said limiting means, a normally closed valve for establishing a connection between the pump outlet and the liquid pressure operated means, and means responsive to the differential of pressure of the liquid anterior and posterior of said interposed valve for opening said normally closed valve.

8. Apparatus for controlling the intake pressure in a supercharged internal combustion engine having in combination, a throttle valve movable to diiierent positions to variably control said intake pressure, automatic control means operable to move said throttle to maintain some selected pressure, a control lever movable to different positions to select a pressure to be maintained and to control the datum of said automatic control means, apparatus for effecting the injection of a liquid into the engine intake to prevent detonation, lmeans normally operative to limit the intake pressure obtainable by movement of the throttle valve to a value required for safe operation of the engine without liquid injection, means for disabling said limiting means and means for preventing operation of the disabling means if the means for injecting anti-detonant does not function.

9. Apparatus for controlling the intake pressure in a supercharged internal combustion engine having in combination, a throttle valve movable to dierent positions to variably control said intake pressure, automatic control means operable to move said throttle to maintain some selected pressure, a control lever movable to different positions to select a pressure to be maintained and to control the datum of said automatic control means, apparatus including a liquid spray nozzle communicatingwith the engine intake for effecting the injection under pressure of a liquid into said intake to prevent detonation, means normally operative to limit the intake pressure obtainable by movement of the throttle valve to a value required for safe operation of the engine without liquid injection and means f 13 4 responsive to the ow of liquid through said nozzie into said intake for disabling said limiting means. n

10. Apparatus for controlling the intake pressure in a supercharged internal'combustion engine having in combination, a throttle valve movable to different positions to variably control said intake pressure, automatic control means operable to move said throttle to maintain some selected pressure, a control lever movable to difl ferent positions to select a pressure to be maintained and to control the datum of said automatic control means. a liquid supply tank, a liquid spray nozzle supplied from s aid tank and communicating with the engine intake, a pump for forcing liquid from the supply tank through the nozzle. means controlled by engine intake pressure and altitude pressure for causing the pump to operate, means normally operative to limit the REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Nam'e Date 2,031,527 Dodson Feb. l, 1936 2,392,565 Anderson et al. Jan. 8, 1946 

